Aim: to study the electric resistance of the crownsurface of tooth.
目的：研究牙冠表面电阻状态。
2
Objective to evaluate the effect to caries of the fixed appliance by the investigation of plaque index on the crownsurface of teeth at the different stages.
目的通过调查固定矫治器治疗中牙冠表面托槽周围的牙菌斑指数评价固定矫治器对龋病的影响。
3
Conclusions Applying 30% supersaturated potassium oxalate to block dentinal tubule could prevent or reduce crownsurface discoloration effectively after front teeth canal therapy.